The present invention relates to apparatus and methods for resisting fouling and, more particularly, to apparatus and methods for resisting fouling in spark plugs, engine parts and exhaust gas recirculation systems.
Fouling by carbon deposits on the spark plug insulation allows the electric charge to the center electrode to run to earth rather than jump across the plug tip. In the extreme, this results in no spark or it may just reduce the spark intensity causing incomplete burning of the gas/air mixture, resulting in a loss of engine efficiency and promoting further fouling. Fouling is more prone to occur if the engine is only used for short periods so that the engine, and hence the spark plug insulator, never get hot enough to burn or vaporize liquid gasoline that is deposited on them.
Various engine parts, such as exhaust gas coolers, exhaust valves, and turbocharger compressors/turbines may also be prone to fouling. New diesel exhaust gas recirculation systems (high pressure loop and low pressure loop), required for complying with emissions control standards, are also prone to fouling. Fouling allows a loss of efficiency, leading to about 3 to 6 percent increase in fuel consumption, as well as durability and reliability issues. Functional failure of these system components due to fouling can lead to emissions noncompliance. This can result in government fines.
The cost of heat exchanger fouling due to cleaning, fluid treatment, additional hardware, and loss of production has been estimated at approximately 0.25% of the GDP. Compact heat exchangers are generally designed with 15-25% excess surface to accommodate the fouling related drop in heat transfer capacity. Also, there is an increase in gas side pressure loss due to fouling which results in an increase in vehicle fuel consumption of up to 6%.
As can be seen, there is a need for apparatus and methods for reducing fouling of spark plugs, heat exchangers and other engine parts.